1. Field
The presently disclosed subject matter relates to a vehicle lightening unit.
2. Description of the Related Art
Conventionally, there is known a vehicle lightening unit in which light emitted from a light source is made to be light in a desired light-emitting mode in a light guiding body so as to be emitted from the lightening unit, for example, according to Japanese Patent No. 4113111 (Patent Document 1), Japanese Patent Application Laid-open Publication No. 2005-11704 (Patent Document 2), Japanese Patent No. 4108597 (Patent Document 3), and Japanese Patent Application Laid-open Publication No. 2007-250233 (Patent Document 4).
Patent Documents 1 and 2 disclose vehicle lightening units in each of which a light source faces straight ahead to the front of the lightening unit, namely, faces in a light emitting direction of the lightening unit, and a light guiding body is disposed to cover the front of the light source from above to below the light source (in the up/down direction). Light emitted from the light source enters the light guiding body, branches in the up/down direction, and is internally reflected twice in the front/back direction. Thereafter, the light is emitted from an exit surface of the front surface of the light guiding body. In the lightening unit disclosed in Patent Document 1, the light guiding body touches an exit surface of the light source. On the other hand, in the lightening unit disclosed in Patent Document 2, there is a gap between the light guiding body and an exit surface of the light source.
Furthermore, Patent Documents 3 and 4 disclose vehicle lightening units in each of which a light source faces downward, and a light guiding body is disposed below the light source. Light emitted from the light source enters the light guiding body, and is internally reflected once in the front/back direction. Thereafter, the light is emitted from an exit surface of the front surface of the light guiding body. In the lightening unit disclosed in Patent Document 3, the light guiding body touches an exit surface of the light source. On the other hand, in the lightening unit disclosed in Patent Document 4, there is a gap between the light guiding body and an exit surface of the light source.
However, in the lightening units disclosed in Patent Documents 1 and 2, the light source faces in the light emitting direction of the lightening unit, and accordingly, the light guiding body which takes in the light emitted from the light source is disposed to cover the front of the light source in the up/down direction, as described above. Consequently, the light guiding body becomes long in the up/down direction, and accordingly, the change of the lightening unit in thickness becomes large, the thickness which is the length in the front/back direction. That makes it difficult to accurately form the light guiding body made of transparent resin.
On the other hand, in the lightening units disclosed in Patent Documents 3 and 4, since the light guiding body is disposed below the light source, the lightening units disclosed in Patent Documents 3 and 4 can be manufactured to be smaller in the up/down direction than the lightening units disclosed in Patent Documents 1 and 2. However, in the lightening units disclosed in Patent Documents 3 and 4, the light is internally reflected only once in the front/back direction, and is emitted from the light guiding body thereafter. Consequently, the length of the light guiding body in the front/back direction becomes long.
Furthermore, in the lightening units disclosed in Patent Documents 1 and 3, since the light guiding body touches the exit surface of the light source, a problem (heat distortion of the light guiding body, for example) may occur because of heat generated by the light source.